1. Field
Methods and apparatuses consistent with embodiments relate to a microplate stacker, and more particularly to a microplate stacker, for microplates with lids, that is capable of extracting standard microplates with lids from the bottom of a stack of microplates and lids, as necessary for processing and stacking the microplates and lids.
2. Description of Related Art
The American National Standards Institute (ANSI) has published a standard generated by the Society for Laboratory Automation and Screening (SLAS), ANSI/SLAS 1-2004, which describes standard microplate dimensions.
FIG. 1 illustrates a microplate 1 including wells 2, according to the ANSI/SLAS 1-2004 standard. The microplate 1 illustrated in FIG. 1 includes 96 wells 2, but the quantity of wells 2 may differ according to the format of the microplate 1.
Microplate manufacturers typically provide one or more standard lid types that are compatible with the manufacturer's microplates. The purpose of the microplate lid is to protect the contents in the microplate wells from external contamination, from cross contamination between the wells, and to limit evaporation of fluid from the wells. Well contamination is of particular concern when working with live organic cells.
FIG. 2 illustrates a microplate 1 having a lid 3 according to the ANSI/SLAS 1-2004 standard and Microplate Footprint Dimensions. As illustrated in FIG. 2, the lid 3 is configured to be seated on top of the microplate 1.
FIG. 3 illustrates a stack of microplates 1 and lids 3 according to the ANSI/SLAS 1-2004 standard and Microplate Footprint Dimensions.
As illustrated in FIG. 3, in addition to being seated on top of its microplate 1, the lid is further configured to act as a base upon which a next microplate 1 is to be nested in the stack of microplates 1 and lids 3. By stacking the microplates and lids, the microplates and lids may be efficiently processed and stored.
Microplates may be processed in a variety of laboratory instruments, such as liquid dispensers, washers, and readers. A “stacker” is one such automated system.
FIG. 4 illustrates a conventional stacker.
As illustrated in FIG. 4, the conventional stacker includes a stack of microplates 4 stored in a source cassette 5. The microplates in the stack of microplates 4 may be individually removed from the cassette 5, typically from the bottom of the source cassette 5. The microplate removed from the stack of microplates 4 may then be presented to a laboratory instrument for processing. After processing, the stacker stores the microplate in a destination cassette 7 for stacking processed microplates.
Microplate “stackers” are commonly available. Examples include the BIOTEK BIOSTACK and TECAN CONNECT MICROPLATE STACKER. Stackers are characterized by the ability to load and unload microplates from the bottom of the stack, and are typically more compact and lower cost than the more sophisticated automatic systems. Such stackers, however, are incapable of removing and replacing microplate lids.
Conventional stackers generally work under the following principle characteristics, which will be discussed with reference to FIGS. 5 to 10.
As illustrated in FIG. 5, a stack of microplates 4 is loaded into a cassette 8, sliding down to the bottom of the cassette 8 by gravity, with the lowermost microplate resting upon support features 9 located at the base of the cassette 8.
The support features 9 may be positioned on inner peripheral edges of a wall of the cassette 8, as illustrated in FIG. 5.
As illustrated in FIG. 6, a lift mechanism 10 may be disposed beneath the support features 9 for raising and lowering the stack of microplates 4 loaded into the cassette 8.
As illustrated in FIG. 7, in operation, the lift mechanism 10 lifts the lowermost microplate, and thus all microplates in the stack of microplates 4, off of the support features 9. The lift mechanism 10 may be disposed on an inner central portion of the cassette 8. Once the lift mechanism 10 has lifted the stack of microplates 4, the support features 9 are retracted. The support features 9 may be retracted by cam motion 11 or any actuating mechanism, motor, etc.
As illustrated in FIG. 8, the lift mechanism 10 is lowered a predetermined distance such that the support features 9 are aligned with a gap (α) that exists between the bottom flange of the lowermost microplate, and the bottom of the microplate above the lowermost microplate.
As illustrated in FIG. 9, once the support features 9 are positioned by the lift mechanism 10, the support features 9 are extended.
The gap (α) into which the support features 9 extend is typically 4 mm to 12 mm.
As illustrated in FIG. 10, the lift mechanism 10 is lowered. Accordingly, the lowermost microplate 1 is lowered and separated from the stack of microplates 4, while the remaining microplates remain in the stack of microplates 4 due to support by the support features 9.
Once removed from the stack of microplates 4, the microplate is then passed to an attached laboratory instrument through any combination of conveyors, articulating robots, etc.
A shortcoming of the conventional stacker described above is that, when processing microplates with lids, there is minimal or no spacing 11 between the lid of the lowermost microplate, and the base of the microplate above the lowermost microplate. Accordingly, the support feature cannot reliably be extended to support a selected microplate, as illustrated in FIG. 11. Removal of microplates from the stack of microplates, therefore, becomes difficult or impossible.
To solve the aforementioned shortcomings, a microplate lid described by U.S. Pat. No. 6,254,833 proposes a lid with recesses in the sides, whereby a lid may be separated from its microplate within a stacker with elevator, by use of support features within the stack. A drawback of the design is that the user is limited to a specific microplate and lid manufacturer.
Alternatively, microplate “delidders” are commonly available. The THERMO SCIENTIFIC MICROPLATE DELIDDER is one such example. Separate delidder stations of this type are commonly part of a larger automated system including an articulating robot (i.e. a robot capable of reaching multiple stations—plate storage stations, delidder, and laboratory instruments). The drawback of such a system is the added expense, complexity, and size of the multiple components, particularly when used in small and medium sized laboratories.
Automated robot systems capable of removing microplate lids are also commonly available. The HUDSON ROBOTICS PLATECRANE EX is one example. Such systems typically include an articulating robot that uses a gripper mechanism to retrieve microplates from the top of a stack of microplates. The robot typically includes a vacuum suction cup, gripper, or other mechanism to lift the lid from the microplate (delid the microplate). The drawback of such a system is the added expense, complexity, and size of the robotic system.
It is therefore an objective of the present application to provide a microplate stacker with integrated capability to remove and replace standard microplate lids. As a result, the aforementioned drawbacks of conventional stackers, delidders, and automated systems may be overcome.